The present invention relates to a device for delivering intense heat to tissue inside the body of a patient for medical applications.
Several medical applications require the delivery of high local doses of heat. For example, tumors, warts, and other non-desired tissue growths can be treated by the application of heat to a localized site of the tissue growth. Sufficient application of heat will cause the death of cells near the localized site of heat release. Typically, the temperature necessary to kill tumor cells is in the range of about 43xc2x0 C. to about 47xc2x0 C., while at the same time the temperature of normal tissue should be kept below about 43xc2x0 C.
Localized heat release, or generation, has been achieved by several means. Current approaches for heating tissue include: gamma radiation, lasers, ultrasound, microwave, radio frequency waves, resistance heating, and hot water heating.
One such gamma radiation system is sold under the name GAMMA KNIFE (Elekta Instruments S.A.) and another gamma radiation system is described in U.S. Pat. No. 5,528,561. Multiple beams of ionizing radiation are directed through a patient. The individual beams of ionizing radiation are reduced to minimize the damage to healthy tissue through which the radiation passes while providing a high dosage of radiation to a target region of tissue. The multiple beams are focused and provide a higher dose of radiation at the point of intersection of the multiple beams. Another method involves moving one or more beams of radiation, so that the beams pass through healthy tissue a limited number of times, while passing through the target tissue repeatedly.
Devices for treatment with lasers or photodynamic methods are described in U.S. Pat. Nos. 5,707,401; 6,379,347; 4,737,628 and 4,872,458. The lasers are used to heat the target tissue to a temperature that destroys the target tissue. In some cases, such as for external target tissue, i.e., skin, the tissue is heated until it vaporizes. In order to use the laser to heat the target tissue within the body, the laser requires a guide tube that is generally heat resistant, so as not to heat healthy tissue surrounding the guide tube as the guide tube enters a patient""s body.
Ultrasound methods are described in U.S. Pat. No. 5,354,258. While ultrasound can be used, ultrasound also heats up surrounding tissue in the process of heating up target tissue within a patient""s body.
Microwave devices have been developed for hyperthermia treatment. One such device is described in U.S. Pat. No. 6,275,738, and treatment is achieved by positioning a radiating antenna system within the tissue to radiate electromagnetic energy into the tissue to be heated. There is a plurality of antenna elements for receiving and reflecting the radiated electromagnetic energy, which involves subjecting the tissue to electromagnetic fields and some heating of the surrounding tissue.
Another method using electromagnetic radiation is treatment with radio frequencies, and descriptions are found in U.S. Pat. Nos. 4,290,435; 5,186,181; 6,337,998; 5,251,645; and 4,679,561. These methods use radio frequencies or other high frequency radiation methods to heat a volume of tissue located within a patient. The tissue is heated by passing high frequency electromagnetic radiation through tissue positioned between two external electrodes located near or in contact with the patient""s skin.
Another method for hyperthermia treatment is the use of pulsed electromagnetic radiation, as described in U.S. Pat. No. 5,776,175. This method includes providing a pulsed radiation output from a radiation source and directing the pulsed radiation output toward a tumor.
A significant drawback to each of these methods is subjecting the body to strong electromagnetic fields and often the surrounding tissue is subjected to the radiation, but in lower doses.
Micro-combustion can be used to provide direct heat transfer for local hyperthermia. The use of direct heat transfer overcomes limitations of other methods of hyperthermia treatments by providing a higher heat flux, enhanced localized heat release by fluid exchange, and reduced thermal damage to tissue surrounding a target region.
The present invention provides a device for generating high intensity localized heat. The system includes a conduit having a supply end and a delivery end, and a catalyst located in proximity to the delivery end. This invention provides a device for generating and controlling an exothermic chemical reaction, and can be termed xe2x80x9ca combustion needlexe2x80x9d.
In one embodiment, the invention further includes a mixing unit. The mixing unit mixes the reactant gases for delivery of a mixture to the supply end of the conduit. The mixing unit provides for a well-mixed gas composition to provide a substantially complete reaction of the mixture.
In one embodiment, the invention further includes an electrolyzer. The electrolyzer provides stoichiometric amounts of gas for mixing in the mixer. The electrolyzer further provides rapid and precise control over the delivery of reactants to the mixer and subsequent rapid and precise control over the generation of heat with the combustion needle.
Other objects, advantages and applications of the present invention will become apparent to those skilled in the art from the following detailed description.